Percutaneous image-guided cryosurgery has become an alternative Minimally Invasive Surgical (MIS) modality for the focal treatment of certain cancers, such as prostate cancer (Katz, A and Rewcastle, J. The current and Potential Role of Cryoablation As a Primary Therapy for Localized Prostate Cancer, Current Oncology Reports 5:231-238, 2003). Use of multiple thin cryoprobes has enabled shaping of the ice balls formed thereof to the prostate lesion and ultrasonographic guidance have yielded better results in terms of local eradication. Investigators have reported good intermediate-term results of cryoablation (CA) when used for salvage in post-radiation patients and for primary cancers (Onik G. Image-Guided Prostate Cryosurgery: State of the Art, Cancer Control 8(6):522-531, 2001). When used for those procedures the technique produces outcomes similar to brachytherapy and three dimensional conformational radiotherapy. The main advantages of cryosurgery include the ability to re-treat patients without added morbidity and to treat salvage post-radiation patients with acceptable results and morbidity. Recent publications demonstrate durable efficacy for cryoablation which are equivalent to other therapies for low-risk disease and possibly superior for moderate to high-risk prostate cancer. However, the multi-focal nature of prostate cancer as well as the biochemical recurrence rate associated with salvage post-radiation or primary cryoablation of localized cancers suggests that there are residual patches of untreated tumor cells in a significant number of cases (De La Taille, et al Cryoablation for clinically localized prostate cancer using an argon-based system: complication rates and biochemical recurrence. BJU 85(3):281-286, 2000). New focal treatments are needed that can be precisely delivered into tumors that cannot be effectively treated by CA alone.
Combined local therapies, such as cryosurgery and radiation or cryoablation and intratumor injection of cytotoxic drug(s) or chemical adjuvants, i.e. “cryochemotherapy,” have become a promising alternative method for physicians attempting to overcome limitations of the current treatment (Han, B, et al. Improved cryosurgery by use of thermophysical and anti-inflammatory adjuvants. TCRT, 3,103-111, 2004 and Tian-Hua, Yu, et al. Selective freezing of target biological tissues after injection of solutions with specific thermal properties. Cryobiology, 50, 2, 174-182, 2005). Although results have been inconsistent, cryosurgery has also been associated with systemic chemotherapy to increase its local efficacy. For example, in vitro experiments using a combination of free drug, 5-fluorouracil (5-FU), given for 2 to 4 days prior to freezing of a human prostate cancer cell line, PC3, resulted in an increased kill efficacy of cryoinjury (Clarke, D M, et al Chemo-Cryo Combination Therapy: An Adjunctive Model for the Treatment of Prostate Cancer. Cryobiology. 42, 274-285, 2001). Interestingly, the drug and cryosurgical regimen were used at levels individually ineffective. In 2002, scientists reported similar results in vitro with the concomitant use of a single freeze-thaw cycle and free bleomycin on B16 F0 melanoma cells, where the membranes of the frozen cells became more permeable to the drug (Mir, LM and Rubinsky, B. Treatment of Cancer with Cryochemotherapy. British Journal of cancer 86, 1658-1660, 2002).
Cryosurgery is recognized as an efficient, thermo-ablative, minimally invasive, method for a large number of solid tumors like prostate, lung, liver, kidney, to cite only a few. Cryosurgery affects tumor tissue viability in three different ways with immediate and delayed alterations: freezing of tumor cells, tumor kill through direct cell alterations, and indirect vascular occlusion. Recently apoptosis, a programmed, gene-regulated cell death, has been shown predominant at the margins of a cryolesion, both at freezing and sub-freezing temperatures and is thought to be another mechanism of cellular killing consecutive to cryothermal changes.
To achieve cryoablation, the entire tumor must be frozen to “kill” temperatures in the range of −40° C. The Freeze/Thaw (F/T) cycle must be repeated, and the kill temperature, out to the tumor margins, must be maintained for a few minutes, and designated as “hold time,” during cryosurgery. Despite a strict adherence to these time-consuming standards, certain tumors like prostate or metastatic liver cancer show a 20 to 40% post-procedure recurrence. Whether the cause of this failure is disease-based or technique-related, it is recognized that cryosurgery needs the support of adjunctive therapy in the form of chemo- or radiotherapy to increase the rate of cell death at margins of the cryogenic lesion where the cell fate is known to be in balance for several days post treatment.
The pretreatment of a tumor with a pro-inflammatory protein like Tumor Necrosis Factor-alpha, based on the hypothesis that vascular-mediated injury is responsible for defining the edge of the cryolesion in microvascular-perfused tissue, augments the cryoinjury that occurs at much higher temperatures, close to 0° C., due to an inflammatory pre-sensitization of the microvasculature (Chao, BH and Bischof, JC. Pre-treatment inflammation induced by TNF-alpha augments cryosurgery injury on human prostate cancer, Cryobiology 49(1):10-27, 2004). Although this pretreatment seems better in terms of ablation completeness, it doesn't act directly on tumor cells and particularly on cells that may have escaped the margin of the cryolesion.
Hence there is a clear need for agents, neo-adjuvant or adjuvant to cryosurgery that could increase the cryosurgical kill as well as the tumor cell kill within and outside the frozen region, while sparing the normal cells and tissue structures.
Systemic chemotherapy has long been used to enhance the kill effect of cryosurgery on experimental and human solid tumors, but results have been inconsistent. This inconsistency could be the result of the fact that combined treatments were not based on sound protocols defining the drug, dosages, route of administration and timing of applications. Since most common chemotherapeutic drugs initiate apoptosis in cancer cells, and given that a similar effect is observed with sub-freezing temperatures, the timely conjunction of each method has been sought for optimizing tumor cell death at tumor margin.
Several papers have shown that in vitro moderate freezing temperatures combined with low dose chemotherapy increased the rate of cell death for prostate and colo-rectal cancer cells. However, these findings were not transferred to in vivo experiments. Several drawbacks associated with using systemic chemotherapy include unpreventable side effects, intermittent tumor exposure to therapeutic doses, and unpredictable tumor penetration. Moreover, tumor cells need to be frozen which increases the risk of damage to neighboring normal tissue by excessive freezing. The cytotoxic drug penetration into the tumor may be difficult and imprecise upon initiation of cryo-induced microvascular impairments particularly if a precise timing between the drug administration and the cryo-application has not been properly coordinated. The drug properties are also critical and should be selected on the basis of their ability to act on the tumor cells as well as on the microvascular network constituents.
There is a need for a more effective cryochemotherapy combination that would increase the tumor cell kill both in the frozen and unfrozen regions of the cryo-application and expose the cells and/or the microvascular bed to effective concentrations of drug for longer durations, while preventing systemic adverse effects.
Intra-tumor chemotherapy using different drugs and vectors or carriers of those drugs has been proposed to improve local delivery of chemotherapeutic agents and to decrease their side effects. These new formulations, such as microspheres, liposomes, and matrixes, have the capability of slowly releasing the active component at therapeutic dose by diffusion through membrane and/or progressive degradation/lysis at body temperature. Such sustained release exposes cells to higher concentration of the cytotoxic drug for longer periods of time, prevents side effects, and results in better outcome. Drug carriers deposited locally or into the vascular bed of the tumor as the sole treatment and/or as a pre-adjuvant or adjuvant therapy to surgical excision, radiation therapy, 5-FU encapsulation and glioblastomas, are taught in U.S. Pat. No. 6,803,052, or microwave hyperthermia, as taught in U.S. Pat. No. 6,788,977 and U.S. Pat. No. 6,623,430. For the latter, moderate hyperthermia of the target organ is triggering the release of the drug out of the thermo-sensitive, solid-matrix microsphere containing doxorubicin, THERMODOX. For safety and efficacy, these treatments rely on the precise, homogeneous deposition and known degradation rates of the carriers. Since these carriers can not be imaged, there is no method to determine, in real time, the optimum delivery, in terms of spatial distribution, and dose. Such assessments are based only on direct visualization during open surgery and on indirect measurement of tissue temperature.
Cryosurgery has been associated with curettage and topical chemotherapy with 5-FU for the treatment of actinic keratosis (AK), a pre-cancerous lesion that usually does not metastasize. One of the topical ointments CARAC CREAM contains 0.5% fluorouracil, with 0.35% incorporated into a patented porous microsphere, MICROSPONGE, composed of methyl metacrylate. However, the prescribed mode of application does not call for a specific geometric deposition of the cream, i.e. preferentially at lesion margins, or timing between cryoablation and chemoablation. As a result, the method is not optimized to increase the cryo-kill at warmer temperatures nor does it spare the neighboring normal skin.
Various drug mixtures and carriers containing cytotoxic agents have also been injected directly into the vascular bed of tumor through selective or supra-selective catheterization with adapted instruments. The combination of cytotoxic drug with agents of embolization is used to increase the cell death rate by submitting the tumor cells to elevated drug concentrations and ischemia consecutive to microvascular thrombosis. However, embolization techniques are not easy. They require specific and costly technologies, highly specialized departments, and the drug distribution is not necessarily homogeneous.
A major drawback of the sustained-release drug carriers, such as delivery carriers like microspheres, liposomes, microcapsules, and gel-foam particles, is that they are not continuously visible using most of the available real-time visible clinical imaging systems, i.e. ultrasound imaging, C-T radiography or fluoroscopy. As a consequence, the physician is unaware if the desired target site of deposition has been reached or if the drug carriers are correctly distributed throughout the tumor or target tissues. To compensate for this drawback, mixtures or emulsions of insoluble contrast agents, like ETHIODOL carriers, have been mixed with the drug solutions or carriers just prior to administration. However since the carrier and the contrast agent diffusion/distributions in tissues are different, the imaging of the contrast in the mixture does not give a precise location of the carrier beyond a short period of time. A further drawback is that pinpoint placement of the depots into the tumor requires the surgeon to have unobstructed views of the delivery device until the delivery tip reaches the targeted tumor region, particularly for deep-seated lesions. Although a number of techniques have been described to increase the echogenicity of delivery needles or catheters during various procedures, their characteristics are not helpful for visualization in deep-seated lesions, where their effectiveness would be most desirable.
Drug release from biodegradable carriers is an important aspect of its use. Common methods include spontaneous release at core body temperature by matrix degradation or diffusion outward from matrix spheres and substrates. For most of these carriers drug release is slow and cyclic which lowers anti-tumor efficacy. Controlled release aims at increasing effectiveness of the drug by immediate and/or sustained release of a large volume of the drug. It prevents complications, such as embolization, from carriers that have unwillingly moved to unwanted location, and allowing for combined technologies that sensitize tumor cells by increasing their permeability to the drug.
Finally, since the cellular heterogeneity of malignant tumors is one of the major factors that explain tumor resistance to an initially effective single drug chemotherapy it would be an advantage to encapsulate a mixture of drugs that would overcome this chemo-resistance. Currently available sustained release systems encapsulate only a single drug.
There is a need for a minimally invasive, combined cryoablation method that would simultaneously expose the periphery of a tumor to effective concentrations of agents for longer durations while preventing systemic adverse effects and preventing further damage to normal healthy tissues. Such a method would enhance safety and efficacy of cryoablation with injection of cancerous disease inhibiting therapeutic agent.